[Functional changes of the endothelium and atherosclerotic process]

The aim of this review is to summarize the current concepts concerning the active role of the endothelium in the pathogenesis of atherosclerosis. Activated endothelium may promote the adhesion of monocytes and their transmigration into the intima. The coordinated expression of adhesion molecules of the selectin, integrin or immunoglobulin superfamily on the surface of endothelial cells and of monocytes modulates these events. The role of lipoproteins and their oxidative derivatives as well as that of selected cytokines and platelet activated factor in initiating changes on the endothelial cell surface has been investigated: these events are associated with an increased endothelial permeability to lipids and lipoproteins with their accumulation in the subendothelium. Once migrated into the intima, monocytes undergo morphological and functional modifications leading to the generation of a polypeptide mediator network which is instrumental in the migration, differentiation and proliferation of smooth muscle cells. Mediators produced by macrophages infiltrating the atherosclerotic plaque and by the endothelium may render the surface of the endothelial cells thrombogenic thus favoring thrombotic occlusion. In conclusion, the most recent studies suggest that the endothelium plays an active role in the pathogenesis of atherosclerosis.